High temperature conversion process



June 28, 1960 E. o. STOKES ETAL 2,943,042

HIGH TEMPERATURE CONVERSION PROCESS Filed April 24. 1957 QUENCH t l4 l5TO PRODUCT i RECOVERY 2 4 l2 HEATER zomz 6 FEED EXTRANEOUS l2 FUEL g:

g :REACTOR ZONE t3 6 AIR IO 9 t Fig. I

By- 18% Attorney Inventors greatly aifect solids circulation.

U ited S a Patent HIGH TEMPERATURE CONVERSION PROCESS Edward DavidStokes and Everett Heath. Spencer, Baton Rouge, La., assignors to EssoResearch and Engineering Company, a corporation of Delaware Filed Apr.24, 1957, Ser. No. 654,741

3 Claims. (Cl. 208-127) The present invention relates to an improvedhydrocarbon, conversion system. More particularly, it deals. with hightemperature cracking of hydrocarbon oils within. a single vessel by theapplication of circulating high density contact, solids.

As is well known, the petroleum industry has. fairly recently developeda process for cracking hydrocarbon feeds to lighter products bycontacting heavy oils with a relatively turbulent bed of hot particulatesolids, the process commonly referredto as lluid bedcoking, Whentreating heavier petroleum feeds, inert solids such. as. coke. sand.glass beads and the like; are. conventionally employed as the contactparticles. Heavy petroleum feeds amendable to such. treatment arecrud'es, topped crudesi. residue. atmospheric andvaeuum bottoms, etc.,yp callyhaving any initial boiling point. of; about; 70.0 F; or higher,an A.P.I. gravity of about, 0?.to- 20, and. a Conrads n. carbon, residueontent. of. about 5. to 40 wt.

percent.

The oil, upon contact with, the hot solids, is converted to vaporousreaction products and carbonaceous residue which is deposited upontheisol ids'i forming a carbon coating-thereon. Generally, at least aportion of 'theparticles coated in. this. manner are withdrawn from. thereaction bed and circulated. to aburner' zoule'wherein oxidation of thecarbonaceous. deposits. serve; to-heat. the solids to req isite, thermalcracking. temperatures... Under some conditions f operation. it. maybedesirab e; to intro e an xtraneous. feed. into the. urner as additional:supply of combustible material. The solid particles, are thenrecirculated to the coking bed thereby. supplying the thermalrequirement of the, conversion process,

Recently, there has been an increasing demand for converting heavyhydrocarbon oils to light. unsaturated products such as ethylene. and.propylene. These. low molecular weight unsaturates and aromatics are ofrelatively high value, finding use in the production of chemical andchemical intermediates. Towards. the. end of obtaining suchvaluableproduct. distributiongthe. transferlineor dispersed phasecokingprocess has. been developed. Thetransfei:- linecoking processcomprises contactinga heavy oil with a rapidly flowing stream, of solidsmaintained at a temperature above, 120.0? E. for reaction 2,943,042Patented June 28, 1960 ICfij Hence, there is considerable need. for ahigh temper ature reaction system wherein contact time is easilycontrolled and. a sufiicient supply of solids .is always present in.the. reaction zonev to receive. the oil feed. 7

In accordance with. the present invention, .hightemperature, short,contact time hydrocarbon reaction is .accomplished in a simplifiedconversion system under dense bed conditions. More particularly,: highdensity solids are circulated between heating and reaction zones withina. single vessel system, oil feed being injected at. asuitable. pointvin the dense phase'reaction zone to provide the desired conversionresidence time.

The. various aspects of the present invention will be made. more clearlyapparent-in the light of the. following. description, drawing andaccompanying example.

Figure I depicts the simplified conversion system of the presentinvention, consisting primarily of reactor zone 1 and heater zone 2.

Figures II and III present modificationof heater zone solid inletconduit 3., I v

Turning to Figure 1, there is shown the conversion vessel of the presentinvention consisting primarily of reactor zone 1 and heater zone 2,,said-zones-being connected by conduit 3 and U-shaped passageway 7.Reactonzone' 13 has an inside diameter of 12 feet as compared to thefoot: diameter of the heater section. As measured from the residencetimes of 0.01 to 5.0 seconds. preferably about 0.01 to 1.0 second..Solids suitablefor this process are the same as those cited above forfluid bed reactions, range in size from. about 0. to 4.00 microns andhave a reaction zone density of 0.5 to 10 lb./ft. I Ihegaseous productsof thisliiglr temperature shdthresidence: time reaction are thenseparated from the contact. solids by c nventional means. such-jas-v a.cyclone-separator, solids being circulated to a, burner vessel. in.muchthe same manner as in dense bed'operations. a

A more complete description. or: a A transfer line: process may be foundin U.S. 2,731,508. 7

However, transfer line coking of hydrocarbons. has presented severalproblems, Such" the reaction zone solids are in the formof'a welldispersed, high velocity Stream, ithas proven'to be diflicul't toproperly contact the oil feedwith the flowing particles. Control-ofreaction. times has been troublesome since'slightinterruptions ordeviation fro'm normal conditions in the coking or burnerzones Feedrates, and hence the yields of desiredproducts'are particularlysensitive to such changes in "the quantity of solids circulated."

bottom ofv the U-shaped connecting conduit. 7, theheight of the solidsbeds. normally supported in the reaction zone and heater Z'one'are e.g.40 and 36 feet respectively. In other words, the heater zone. will,during usual operation, containthe major inventory of so'lidswithin theconver sion system. Generally, this will be 80% of the overall solidsinventory; Within heater zone 2 there'is contained a turbulent bed 4 ofdense, large sized inert solids. While mullite is employed" in the.present example, other high density materials such as'iron, sand, andzirconium fsilicate spheres may be alternatively utilized. Thesefcontact solids range in size. from 400m 2000 microns, preferably. averagingabout 50.0 to 1000 microns, and have a true density varying from 150 to500 lbs./ft.

The solids, which are'to. be circulated to the heating zone, generallyhave; a coating of'carbonaceous materi'ai which they have-acquired inthe course of contacting oil feed in the reaction zone, as will be laterfurther described.

Oxidizing gas, preferably air,'is introduced into the heater zone bymeansof line 6'at an overall rate of'27 standard cubic feet/lb.'of'contact solids ci'rculatedbm tween the two zones. The air,maintaining the'heating, zone solids in the form of dense fluidized"mass of}: density of I70 lbs-./ft. ,*servesto oxidize the ciutbonaceo'ns coating-on the contact solids' thereby heating them heat suppliedby the-combustiorrof. this extraneous; fuel.

is. approximately 2000 B..t.u.'filbs.-. of solids circulated. The bedtemperature is. thus about 1.6.0.0. E, or approrde mately to 400greater: thanv the desired conversion: temperature; Flue: gas:issremotved'overhead:bywline 18, and its. heat: content recovered"ifdesirem'by conyem tionalmeans. The system is thereby maintained intheir; mal balance,

In accordancewith the present invention-.90 lbsg "o5 solids/min./ft. ofreactor ClOSS-SCllOIldPifildablS" "th drawn from the heater -zone andpassed: toteac'tors'ection l by means of conduit 7. From its lowermostextremity to the bottom of the heating zone base, the

conduit measures 18 feet.-. The density of the solids therein is 200lbs./ft. Steam is injected into conduit 7 at several points 8, 9 and 10'chosen to ensure smooth circulation of solids. Other propelling gasessuch as N,, light hydrocarbons, or mixtures thereof may be alternativelyutilized. The steam, introduced at an overall rate of 30 wt. percentbased on feed, serves to convey the solids upwardly through the reactionzone as a dense, fluidized solids column 11 having a density of about160 lbs/ft. prior to feed injection.

In order to obtain the desired oil residence times of approximately 0.25second prior to quench, hydrocarbon feed such as an Elk Basin residuumhaving properties tabulated below, is injected in 'theupper portion ofreactor solids column by'means on one, preferably several nozzles 12, atan overall rate of 0.06 lb./lb. of circulating solids. i

TABLE I Feed: Elk Basin crude Gravity, A.P.I 2.4 Conradson carbon, wt.percent 30.0

S wt. percent 3.93 N 'wt. percent 0.603 H/C atomic ratio 1.34

Distillation:

Initial boiling point, P. 883 10% F 1041 20% F. 1070 Upon contact withthe hot, dense mullite particles, the

tion resulting from operating in accordance with the above description.

TABLE II Pr0ducts, on feed H wt. percent Q. .i... .33 CH wt. percent4.50 C H wt. percent 12.55 C H wt. percent -2.40 C H wt. percent "-5.9.80 C H wt. percent .42 C H wt. percent 2.80 C H wt. percent 6.50 C/430" vol. percent 27.0 430/650 vol. percent 21.0 650/1050 vol. percent24.0 1050+ 9.6 Total carbon, wtfipercent 5.1

oil feed is converted at a reaction temperature of 1380 F. to lightgaseous hydrocarbons and carbonaceous material which deposits upon thecontact solid, C5" conversion being about 30 wt. percent. The vaporousreaction products rapidly pass upwards from reaction zone 1 and arewithdrawn overhead through passageway 14;

Since the contact solids are large sized, dense particles, it willnormally not be necessary to employ cyclones or other conventionalgas-solids separators in conjunction with the reaction systems. A solidsseparation efiiciency' of 99% is obtained when solids having a truedensity of 500 lbs./ft. are used as the contact particles. Quenchmedium, such as water, feed stock, or recycle product oil boilingbetween 300 to 600 F., is injected by line 15 into the withdrawn vaporsso as to prevent undue degradation of the desired reaction products. Thequenched ticles so as to remove any occluded hydrocarbons, and

further to maintain a free moving solids flow.

- It is preferred to operate the overall system with the upper level ofreaction bed 11 significantly higher than that of heating bed 4. Thus, asolids seal in conduit'fi prevents heating zone gas from entering theconversion section of the system. However, other means, for examplethose set forth in Figures H and III, can be used in, conjunction withthe relative bed level requirement or entirely by themselves, formaintaining separation of heating and reaction zone vapors.

. It may be desirable, under certain conditions of operation, tointroduce the hydrocarbon oil feed at a lower portion of the reactionbed such as by means ofnozzle, 13. By controlling propelling gasinjection, rate and point of feed injection, desired reaction time maybereadily obtained.

Turning to Figure II, there is shown the section of heater zone 27 inthe immediate vicinity of overflow solids conduit 26. The drawingillustrates the application of a flapper valve 29 attached to wall inlet28 for preventing heating zone vapors from mixing with the productof-the conversion reaction.

Figure HI presents an alternative mode of'accomplishing this end.Structure 38 is designed to confine the entrance of conduit 36' intoheater zone 37 so as to prevent backflow of combustion gases into theoverflow line.

The following table presents a compilation of operating conditionsrelative to the above description.

TABLE III Contact solid: Range Maximum size, microns 600 to 2000 Minimumsize, microns 400 to 700 Average size, microns 500 to 1000 True density,lbs/ft. 150 to 500 Bulk density, lbs./-ft. 110 to 350 Fluidized density,lbs/ft. to 170 Apparatus:

ID. of reaction zone, ft 5 to 20 ID. of regenerator, ft 30 to 70 Reactorbed level height, ft 3 to 60 Regenerator bed level height, ft.. 10 to 60Height of U-seal outlet to heating zone, ft 10 to 30 Process:

Reaction bed temperature, F 1100 to 1600 Regenerator bed temperature, F1200 to 2000 Rgenerator bed density, 1bs./ft. 80 to 170 Density instandpipe from regenerator,

lbs/ft. 100 to 200 Density in reactor, before feed injection, lbs./ft.80 to 170 Density in reactor, after feed injection,

,lbs./ft. 70 to 150 Superficial gas velocity in reactor,

ft./sec. 2 to 30 Solids circulation rate, lbs./min./ft. reactor 50 to300 Feed rate, lbs/lb. solids circulated .02 to .2 Steam rate toreactor, wt. percent on feed 5 to 50 Efliciency of solids separation,percentto Oil residence time before quench, sec- 0.1 to 1.0 C-conversion, wt. percent 20 to 60 Air rate to burner, s.c.f./ lb. solidscirc 20 to 40 Extraneous heat from oil injected into regen., B.t.u.s/1b.solids circ 0 to 3000 Burner hold-up, percent total solids inventory 60to 98 Reactor hold-up, percent total solids inventory 40 to 2 A P oyerreaction zone, p.s.i 6 to 70 fans Numerous modifications may be appliedto the above described system without departing from the spirit of thepresent invention. The present system finds application wherevercontrolled reaction residence times are desired in a simplifiedconversion system. Hence, a broad range of feed materials may beemployed. Catalytic or semicatalytic process conditions may be obtainedby using the appropriate contact particles.

The present invention is not limited to the particular solids flowpattern described. Thus, it may be desirable to flow solids from theheater zone to the upper and/or middle of the reaction solids column.Similarly, the heating zone may be operated as a shot heater, gravitybed, or the like. While a cyclone is normally not re quired when highdensity solids are employed, a solids separator may be inserted in thesystem. In another modification, the area above the reaction zone bedmay be enlarged to compensate for increased vapor velocity due to feedvaporization and thus further minimize solids entrainment.

By operating in accordance with the present invention, contact time iseasily regulated by employing feed and aeration gas as split streamriser gases for controlling solids flow rate and oil residence time.Utilization of a dense phase of large, high density reaction particleseliminates the necessity for cyclone separation of solids andgas-product, and enables both reaction and regeneration to be carriedout in a simplified conversion system design.

Having described the present invention, what is sought to be protectedis concisely set forth in the following claims.

We claim:

1. A process for carrying out high temperature, short contact timereactions in the conversion of residual high boiling hydrocarbons havingan initial boiling point of at least about 700 F. which comprisesproviding a mass of particulate carbonaceous containing solids in aheating zone, said solids having a size ranging from about 400 to about2000 microns and having a true density of about 150 to 500 lbs. per cu.ft., introducing air into the bottom portion of said heating zone at afluidizing velocity to maintain said carbonaceous containing solids as adense fluidized bed while burning carbonaceous material from said solidsand thereby heating the solids to a temperature in the range of 1200 F.to 2000 F., withdrawing heated solids from the bottom portion of saidfluidized bed of solids in said heating zone and passing them through aconfined U-shaped passageway as a dense fluidized mass, introducingaerationgas into the dense fluidized mass of solids in the lower portionof said .U-shaped passageway to reduce the density of the fluidized massof solids and to pass the less dense fluidized mass as a column ofsolids from said U-shaped passageway upwardly through -a verticallyarranged reaction zone as a solids column of much smaller diameter thansaid heating zone, the density of the fluidized solids in said reactionzone being in the range of about 80 to 170 lbs. per cu. ft., injectingpreheated hydrocarbon oil into the upper portion only of said solidsabout 0.1 and 1.0 second, disengaging vaporous unsaturated hydrocarbonsoverhead from the upper end of said solids column in said reaction zoneand recovering the disengaged vaporous unsaturated hydrocarbons, main- 7taining the top of said solids column in said reaction zone at a higherlevel than the top of the dense fluidized bed in said heating zone,overflowing solids from the top of said solids column of said reactionzone into a downwardly inclined confined passageway leading di-' rectlyfrom said reaction zone to the interior of said heating zone below thelevel of solids therein to provide a solids seal to prevent gaseousmaterial intermixing between said heating zone and said reaction zonewhile providing flow of carbonaceous containing solids from the upperend of said reaction zone to said heating zone for heating and recyclingto said reaction zone and maintaining said solids in said downwardlyinclined confined passageway in a fiowable condition.

2. A process according to claim 1 wherein extraneous fuel is introducedinto said heating zone to supply additional heat to said solids.

3. An apparatus for converting hydrocarbon oils which includes a heatingvessel adapted to contain fluidized solids and having a top outlet forgas, means for introducing oxygen-containing gas into the lower portionof said heating vessel, a separate vertically arranged reaction vesselarranged adjacent said heating vessel and having a diameter less thanone-half the diameter of said heating vessel and having substantiallyuniform diameter throughout its length, the bottom of said heatingvessel and said reaction vessel being connected only by a U-shapedchannel, a single conduit extending downwardly at an angle directly fromtop of said reaction vessel to an intermediate portion of said heatingvessel for conducting solids from the top of said reaction vessel tosaid heating vessel whereby solids flow down from said heating vesseland upwardly in said reaction vessel for overflow into said singleconduit and said heating vessel, means for introducing a fluidizing gasinto the lower portion of said U-shaped channel to reduce the density ofthe fluidized solids therein and cause upward flow of a less densefluidized column of solids through said reaction vessel, said reactionvessel having a top outlet at;

a higher level than the inlet to said conduit for removal of convertedhydrocarbon products free of said solids and oil injection meanspositioned along only the upper portion of said'reaction vessel forintroducing hydrocarbon oil thereinto.

Johnson Mar. 22, 1949 Hunter May 27, 1952

1. A PROCESS FOR CARRYING OUT HIGH TEMPERATURE, SHORT CONTACT TIMEREACTIONS IN THE CONVERSION OF RESIDUAL HIGH BOILING HYDROCARBONS HAVINGAN INITIAL BOILING POINT OF AT LEAST ABOUT 700*F. WHICH COMPRISESPROVIDING A MASS OF PARTICULATE CARBONACEOUS CONTAINING SOLIDS IN AHEATING ZONE, SAID SOLIDS HAVING A SIZE RANGING FROM ABOUT 400 TO ABOUT2000 MICRONS AND HAVING A TRUE DENSITY OF ABOUT 150 TO 500 LBS. PER CU.FT., INTRODUCING AIR INTO THE BOTTOM PORTION OF SAID HEATING ZONE AT AFLUIDIZING VELOCITY TO MAINTAIN SAID CARBONACEOUS CONTAINING SOLIDS AS ADENSE FLUIDIZED BED WHILE BURNING CARBONACEOUS MATERIAL FROM SAID SOLIDSAND THEREBY HEATING THE SOLIDS TO A TEMPERATURE IN THE RANGE OF 1200*F.TO 2000*F., WITHDRAWING HEATED SOLIDS FROM THE BOTTOM PORTION OF SAIDFLUIDIZED BED OF SOLIDS IN SAID HEATING ZONE AND PASSING THEM THROUGH ACONFINED U-SHAPED PASSAGEWAY AS A DENSE FLUIDIZED MASS, INTRODUCINGAERATION GAS INTO THE DENSE FLUIDIZED MASS OF SOLIDS IN THE LOWERPORTION OF SAID U-SHAPED PASSAGEWAY TO REDUCE THE DENSITY OF THEFLUIDIZED MASS OF SOLIDS AND TO PASS THE LESS DENSE FLUIDIZED MASS AS ACOLUMN OF SOLIDS FROM SAID U-SHAPED PASSAGEWAY UPWARDLY THROUGH AVERTICALLY ARRANGED REACTION ZONE AS A SOLIDS COLUMN OF MUCH SMALLERDIAMETER THAN SAID HEATING ZONE, THE DENSITY OF THE FLUIDIZED SOLIDS INSAID REACTION ZONE BEING IN THE RANGE OF ABOUT 80 TO 170 LBS. PER CU.FT., INJECTING PREHEATED HYDROCARBON OIL INTO THE UPPER PORTION ONLY OFSAID SOLIDS COLUMN MOVING UPWARDLY THROUGH SAID REACTION ZONE ANDMAINTAINED AT A CONVERSION TEMPERATURE IN THE RANGE BETWEEN ABOUT1100*F. AND 1600*F., CONVERTING SAID